1. Field or the Invention
The invention relates to an arrangement, a system and a method for providing a vehicle, in particular a track bound vehicle, with electric energy by using a receiving device adapted to receive an alternating electromagnetic field and to produce an alternating electric current by electromagnetic induction. In particular, the invention is applicable for providing light rail vehicles (e.g. a tram) with energy for propulsion.
2. Description of Related Art
In particular track bound vehicles, such as conventional rail vehicles, mono-rail vehicles, trolley busses and vehicles which are guided on a track by other means, such as other mechanical means, magnetic means, electronic means and/or optical means, require electric energy for propulsion on the track and for operating auxiliary systems, which do not produce traction of the vehicle. Such auxiliary systems are, for example, lighting systems, heating and/or air condition system, the air ventilation and passenger information systems. However, more particularly speaking, the present invention is related to transferring electric energy to a vehicle which is not necessarily (but preferably) a track bound vehicle. Generally speaking, the vehicle may be, for example, a vehicle having an electrically operated propulsion motor. The vehicle may also be a vehicle having a hybrid propulsion system, e.g. a system which can be operated by electric energy or by other energy, such as electrochemically stored energy or fuel (e.g. natural gas, gasoline or petrol).
Track bound vehicles, in particular vehicles for public passenger transport, usually comprise a contactor for mechanically and electrically contacting a line conductor along the track, such as an electric rail or an overhead line. At least one propulsion motor on board the vehicles is fed with the electrical power from the external track or line and produces mechanic propulsion energy.
Trams and other local or regional trains are operated usually via overhead power lines within cities. However, especially in historic parts of cities, overhead power lines are undesirable. On the other hand, conductor rails in the ground or near the ground cause safety problems.
WO 95/30556 A2 describes a road way-powered electric vehicle system. The all-electric vehicle has one or more on-board energy storage elements or devices that can be rapidly charged or energized with energy obtained from an electrical current, such as a network of electromechanical batteries. The energy storage elements may be charged while the vehicle is in operation. The charging occurs through a network of power coupling elements, e.g. coils embedded in the road way. Inductive heating coils are located at passenger loading/unloading zones in order to increase passenger safety.
Placing the coils at selected locations along the length of the roadway has the disadvantage that the energy storage on board the vehicle needs a large storage capacity. In addition, if the vehicle does not reach the next coil in time, the vehicle might run out of energy for propulsion or other purposes. Therefore, at least for some applications, it is preferred to transfer energy to the vehicle continuously along the path of travel, i.e. along the track.
Inductively transferring energy from the track to the vehicle, i.e. producing electromagnetic fields, is subject to restrictions regarding EMC (electromagnetic compatibility). On one hand, electromagnetic fields may interfere with other technical devices. On the other hand, people and animals should not be subjected to electromagnetic fields permanently. At least, the respective limit values for field intensity must be observed.
As principally disclosed in WO 95/30556 A2, the vehicle which is travelling on the track may comprise a coil and the electromagnetic field generates an electric alternating voltage in the coil which can be used to operate any electric load in the vehicle, such as a propulsion motor, or can be used to charge an energy storage system, such as conventional batteries and/or super caps.